Maybe I dont need the X. I have a 12.5-1, 499 ci. 275 @ .50 and .660 Lift solid roler cam, 8" 5000 rpm converter, 28" tire and 3.73 gears. I was trapping befor at around 6300 rpm. I would assume i should be around the 6500 maybe + a little with the new setup. Prob wont be reving higher then 7000. car weighs 3750 with me in it. Currently runs 10.60's with the stage VI heads and am hoping these TF 270's willadd a little power over my stage Vi's
Your cam might be a little too much duration and not enough lift for the 270 heads. I'd recommend calling Dwayne at Porter Racing Heads and talking to him about your combination. You might pick up some power if you throw more lift at the valves. Not sure what Dwayne will recommend, maybe something in the 272/280 duration at 0.050 and 0.750 lift. Kind of depends which rocker arms you have and how much money you want to throw at the valve train.
